With the increasing number of equipment for underwater or even deep sea exploration and construction, pressure compensation devices are increasingly used for balancing the internal pressure of a power unit in a construction equipment, so as to reduce the requirements on sealing of the power unit. For the power unit with more powerful impact, in order to achieve the sealing effect better, it is best to ensure that the internal pressure of the power unit is slightly higher than the external pressure.
Most of the current pressurized pressure compensation devices are used independently in the construction equipment, but due to an oil leakage of the construction equipment is inevitable, the pre-pressure of the pressurized pressure compensation device becomes smaller gradually, therefore it is often needed to lift the pressure compensation devices out of the water surface for oil refilling manually. The existing pressurized pressure compensation device cannot make a real-time detection of its internal pressurization value, and can only observe the piston position of the pressure compensation device manually to determine whether or not there is a need of oil refilling. This process not only reduces the construction efficiency, and more seriously, water seepage may occur inside the power unit due to a failure of timely oil refilling.